The capsule endoscopy (CE) with the full name of “intelligent capsule digestive-tract endoscopy system” is a noninvasive diagnosis technique developed in recent years, and was approved by the U.S. Food and Drug Administration (FDA) in 2001 for examination of small intestinal diseases. The CE has the advantages of being easily operated, being convenient for examination, being noninvasive, having no pain, having no cross-infection, having no influence on normal work of the patient and the like. By 2009, more than 0.75 million people had undergone the CE examination. Currently, the CE is mainly used for diagnosis of diseases such as obscure gastrointestinal bleeding, Crohn's disease, small intestine tumor and the like, and with the technology development in recent years, a CE used for examination of oesophagus and colon gradually appears, which further widens the application range of the CE and provides great aids for the gastroenterologist. Also, a magnetic assisted capsule endoscopy system capable of observing gastric lesions has already been reported by a study.
However, capsule retention caused by luminal stenosis due to tumors or various diseases is a common adverse event of CE. The small intestine has a smaller diameter as compared with the stomach and colon, and thus the retention of capsule is more likely in the case of stenosis of small intestine. Since the CE is non-degradable, the CE must be removed if retention thereof occurs, otherwise a serious consequence will be caused. Moreover, unlike the stomach and colon, it is difficult to remove the capsule if retention thereof occurs, and sometimes even an laparotomy is needed, thereby bringing great agony to the patient.
Therefore, it is especially important to prevent capsule retention. Currently, the clinician mostly screens patients for CE examination based on medical histories thereof initially, and then further determines whether an intestinal stenosis exists through a contrast examination. However, the accuracy rate of this method is poor, wherein missed diagnosis of some patients occurs, and some patients with intestinal stenosis as determined through contrast examination still can complete the CE examination. Some intestinal stenoses are in the type of functional stenosis, which still can deform to allow pass of the capsule when the CE passes therethrough. The CE examination result of such a patient is often positive, which provides an important basis for diagnosis of the patient. Therefore, there is a need for us to find a more accurate method for judging whether the intestinal condition is suitable for CE examination, which is noninvasive, safe and reliable, neither making the patient be subjected to an unnecessary examination nor causing the patient to lose a good opportunity for definite diagnosis of diseases.
In 2006, Xi-Tian Pi et al. invented a sustained-release tablet for detecting digestive-tract emptying and a process for preparing the same; and in 2010, Elisha Rahinovitz et al. invented a degradable capsule for evaluating whether an intestinal stenosis exists before the CE examination. Both of the aforementioned patency capsules have a similar size to a normal CE, which are taken by a patient before the CE examination, and can be successfully discharged from the body if the digestive-tract of the patient is unobstructed, otherwise the capsules are degraded by themselves with no residue. Also, whether the capsule still exists in the body and the approximate position of the capsule may be determined by X-ray positioning. However, these methods are still lack of accuracy; certain harmful radiation to human bodies is caused by the ray; and the methods are a bit complicated as requiring the aid of an X-ray apparatus.